I Promise
by Iris Omega
Summary: Sometimes, science isn't all that it's cracked up to be. Who ever said that nanomachines were reliable in the longrun? [SvenxEve] Rated T for possible later chapters


**Author's Note**: Phew. Well, it's been _forever_ since I last wrote something. My inspiration for my _Alice 19th_ fanfic has run _completely_ dry. I've been trying so hard to finish it, but everything I come up with is crap. -sigh- Oh well…what's done is done, eh?

Needless to say, I am now absolutely hooked on _Black Cat_. I finished reading the 20th, and final, volume last night. The ending was a bit abrupt, but was practically _begging_ for people to write fanfiction. Plus, I'm in love with the characters, so I couldn't resist.

My two favorite couples are Kyoko/Sheldon and Eve/Sven. I'll probably come out with a Kyoko/Sheldon one-shot in the near future, but I wanted to go ahead and take a stab at an Eve/Sven fic first. I don't know how well it's going to turn out, but I have nothing to lose, right?

I may not even continue it after this chapter. I just wanted to see how many people would be interested in this fic. If someone shows interest, then I'll probably continue. If no one does, then I might not. I'm not really begging for attention or reviews, I just like it when other people enjoy the stuff that I write. That's all. -koff-

So, yes. If you enjoy this little prelude, then please review so I know that someone wants me to continue.

That said…here 'tis!

—

**Disclaimer**: I do not own _Black Cat_. Although, 'twould be cool if I did. Then, like…I could make Kyoko/Sheldon and Eve/Sven canon pairings. And Sephiria/Belze, too! Rinslet/Janus is practically canon, so I don't have to worry about that…

-wanders off, mumbling about random pairings-

—

Eve's ruby eyes were unfocused as she stared at a blank white wall. Her pale blonde hair fell around her face in a somewhat disheveled manner—the edges reaching just below her shoulders, the style somewhat reminiscent of how Rinslet had used to wear her hair. It had been years since she had worn her hair long. Short hair seemed to be more convenient and efficient. Plus, it didn't get in her way as much when she was fighting.

But, then…that didn't matter anymore, did it? Biting her lip lightly, she tightly clenched her blanket with her shaking hands. Just thinking about the situation brought tears to her eyes. Ever since she had met Train and Sven, she had worked so hard to become stronger…she had worked so hard to be able to help them…to _protect_ them someday.

Once again, all of her efforts had been for nothing.

Sven had helped her believe that her powers were actually a blessing, instead of a curse. He had showed her that she could help people, instead of destroying them. She had really believed that she could make a difference. She had really believed that it was what she had been created for. She had really believed that her nanomachines were the things that would give her the ability to become the strongest.

Once again, she had been wrong.

All that she had wanted was to be worthy of staying with Train…and with Sven. She had only acted tough so that they would take her seriously. Although she had never admitted it, every smile and every pat on the back that they had given her had made her want to cry with happiness. She had finally found her calling in life. She had finally found something that made her life worth-while. She had finally found the person who was worth dying for.

Once again, she had failed everyone.

She hadn't seen Train or Sven since they had taken her to Tearju's private clinic. She had been unconscious for most of the journey, but she had been conscious enough to remember the panicked look on Sven's face when she had suddenly collapsed in the middle of the kitchen. For a few weeks, she had been feeling strange and had been making small mistakes whenever they went after criminals, but she didn't think that it was anything serious. Apparently, she had made a bad judgement.

Tearju had been running tests for weeks. Then, one day, she had walked into Eve's room—her lips pursed and her brow furrowed distractedly. Eve still remembered every word that Tearju had said; she remembered every painful detail. She knew that she was sick…_very_ sick, and that there was only one thing that could be done to save her. If she didn't go through with the operation, she would die. It was as simple as that.

But, she wasn't afraid of the operation. She wasn't afraid of what could possibly happen to her. She wasn't even afraid of dying. The one thing that she was afraid of was becoming utterly useless to Train and Sven. She was afraid of being left alone again.

The last time that they had left her, Sven had said that it was for her own safety. When she had shown him that she couldn't just stay with Annette, he had told her that she could continue on with them until she found her own happiness. Maybe he had never realized that her happiness was right there, with _them_. That was her only happiness, and she could never have any other. If they left her, everything would be over.

If they left her, she would die.

—

"…say _what_!"

Sighing, Tearju adjusted her glasses and shook her head slightly. "I assume that your question is rhetorical."

From the blank looks on the faces of both Train and Sven, it was pretty apparent that the question wasn't, in fact, rhetorical. Tearju sighed again.

"Simply enough, Eve has a rare blood disorder. It's destroying her vessels and her immune system, causing the oxygen distribution in her body to diminish. She fainted in the kitchen because she was suffocating, although she may not have felt like it. Her body was oxygen deficient. Plus, she has been struggling with the initial symptoms of tuberculosis. She doesn't have the disease, but her body was simulating it due to her depleted immune system." She paused for a minute for a breath—removing her glasses and polishing them on her sweater. "If I don't do something about her disorder within the next month or two, Eve will die."

Sven stumbled back into his chair, a stunned and stricken look on his face. At first, he had thought that he had heard Tearju incorrectly. But, there was no denying it…Tearju meant what she had said. Train was leaning against the wall and staring at the window—a blank look still plastered on his face. Apparently, he was having a hard time processing the information, as well. Eve had been such a large part of their lives for so many years. If she was gone…

"But, you can save her, right, Doc?" Train's voice was as distant as his expression.

Slipping her glasses back on and pushing them up her nose with a forefinger, Tearju nodded. "I can save her, yes…"

There was a pause. Train looked to Sven, waiting for him to say something, but Sven was simply too shocked to speak. The most that Sven could do was stare and Tearju, attempting to hide his panic. It was pretty obvious to both of them that there was an unspoken "but" in Tearju's speech.

Quirking an eyebrow, Train looked to Tearju. "So, what's the catch?"

Tearju folded her fingers together and leaned back in her chair, her gaze locked on the ground. "Eve's condition is aggravated by the nanomachines in her bloodstream. In fact…my research isn't complete, but…her condition may have been _caused_ by the nanomachines. Even though Eve was created to be a living weapon, she is still a human being. As you know, Eve was one of the first humans used for the testing of nanomachines. Thus, we haven't been able to study the long-term effects that they have on the human body."

Judging by the look on Train's face, almost all of Tearju's technical speech went right over his head. Clearing her throat, she got to the point.

"Basically, the only way to save Eve is by performing a full blood transfusion. However, because of Eve's peculiar body structure, the only blood that I could safely put into her body is mine. If I give up all of my blood, obviously, I'll die. So, what I'm going to do is hook Eve up to a machine that will pull all of the blood out of her body, clean it, and put it back in. The only problem is that there is a forty-percent chance that the transfusion won't work, because the blood won't be clean and fresh—it will still be Eve's blood, just recycled."

"But, there's still a sixty-percent chance that Eve will live. It's better than a zero-percent chance, right…?"

Tearju nodded. "True. Either way, however, Eve will lose her powers."

Train blinked rapidly, while Sven flinched slightly. Eve's powers were everything to her, and they knew it. She had finally come to accept herself as she was—nanomachines and all. Robbing her of her powers was much like literal identity theft. Would she have to find herself all over again?

Still, they understood that it had to be done. Eve's nanomachines traveled to and fro in her bloodstream. If the blood left, so did they. Besides…her life was more important than anything else.

"And…if the transfusion doesn't work…?"

Both Train and Tearju were surprised to hear Sven speak. Train clenched his teeth and went back to staring out the window. Leave it to Sven to think negatively.

"If the transfusion doesn't work…" Tearju trailed off for a moment, biting her lip. Even though she hadn't gotten to know Eve very well, it was an emotional issue for her. Eve was her clone. She was more than just a project to Tearju—she was Tearju herself. In a strange way…Eve was her daughter. The last thing that she wanted to do was watch the girl die. "If the transfusion doesn't work, then we can search for donors so we can give Eve fresh blood. I won't lie, however…the likelihood of that happening is incredibly minimal. Even if there are people out there with a matching blood type, it would take us too long to find them. Eve would…probably die before that would happen."

Sven blew out a breath, covering his face with his hands—his elbows resting against his knees as he leaned forward. He had known what Tearju was going to say. He just needed to hear it from her…he needed to hear it out loud to know that it was real. There was a forty-percent chance that Eve was going to die. There was a forty-percent chance that she would be gone forever.

"Eve has been conscious for a few hours now. I have already explained everything to her. The decision of whether or not to go through with the transfusion is hers." Pausing, she stood up from her desk and walked over to stand in front of Sven. "Before she decides, she wants to see you, Sven. She refuses to even discuss it until she sees you."

Sven looked up, his expression bewildered, then nodded slowly as he attempted to process everything that he had just heard. Tearju went on to tell him what room Eve was in, and how to get there, but he just stared numbly—hardly hearing anything that she said. All he knew was that he just needed to see Eve. Everything else didn't seem to matter at that point.

When Tearju had finished speaking, she stood up and opened the door—watching sadly as Sven walked out, followed by a frowning Train. She opened her mouth to say something, then sighed and shook her head, closing the door behind them.

If there was one thing that she hated most, it was watching hearts break right in front of her eyes.

—

Sven looked like he had just been punched in the stomach. As soon as Tearju had started talking about the likelihood of Eve dying, his mind had gone into over-drive. He had tried to imagine his life without their Princess, but he found that he couldn't. She had been a part of his life for six years. The last time that he had left her, he had fallen into a deep depression; and he had even promised her that they would visit on a regular basis. This time, though…there would be no visitations. He would never see her again.

He walked ahead, hardly knowing where he was going. He knew that he would eventually wind up at Eve's room. Until then…he was lost in his own thoughts—thoughts that he soon began to verbalize, almost without knowing it.

"I always thought that, if Eve died, it would be at the hands of our enemies…it was why I tried so hard to protect her…"

"Sven…" Train's voice carried a warning tone. Sven didn't seem to notice.

"I never thought that she would die like this. She was always so strong, I thought…I thought that she would be the last of us to die. I never saw this coming." He gritted his teeth together, feeling anger suddenly surge inside of him. "I _should_ have seen this coming. She was acting so strangely. I should have done something to help her sooner. Now it's too late."

Train had finally had enough of Sven's whining. Grabbing him by the shoulder, he swung the green-haired man around to face him, then pulled his arm back and slammed it into Sven's face. Taken completely by surprise, Sven stumbled back into the wall—holding a hand up to his face and staring at his partner, mouth slightly agape. For a few moments, Train just watched him with a seething expression. Then, he stepped forward and gripped Sven's shirt—slamming him against the wall. His feline eyes were alight with anger, and his jaw was clenched.

"Here you are, whining about what you didn't do and should have done, already giving up, when Eve is in there fighting for her life! Stop being such a coward!" It took all of the self-control that Train possessed to keep from out-right throttling the man. "The Doc said that Eve has a sixty-percent chance of surviving. Isn't that enough for you!" Disgusted, he let go of Sven's shirt and stepped back—gesturing towards a room with a nod. "She's in there, and she wants to see you. Give her a reason to go for that sixty-percent chance." With that, he turned and stalked away, leaving behind a flabbergasted Sven.

"Train…"

—

Hearing the door to her room open, Eve jumped a bit in surprise and instantly snapped out of her reverie. All at once, her heart both leapt and sank as she watched Sven walk into the room—a completely fake smile plastered on his face. She knew that Tearju had told him everything, and she knew that he was going to try to be strong for her. The corners of her mouth twitched slightly as she attempted to smile in return, but she failed miserably. It was too hard to smile, even if Sven was there.

He sat on the edge of her bed, placing a hand near one of her extended legs as he leaned sideways, his legs hanging over the edge. "Hey, Eve…" His voice was soft—tentative. It was almost as if he thought that he would hurt her if he talked too loudly. Or maybe he was still in shock. "How are you feeling?"

Eve remained silent for a few moments, turning her head to gaze out the window into the trees beyond. When she finally spoke, her voice carried a hollow tone. "You don't have to act like everything's alright, Sven…I know that it isn't."

Sven winced, knowing that she was right. "Eve, I--"

"Are you going to leave me, Sven?"

Surprised at her question, Sven stopped in mid-sentence and blinked rapidly, watching her in disbelief. She was still as calm as ever, staring blankly into the distance. "…what?"

Eve sighed and turned her gaze to the blanket over her lap that her fingers were idly fiddling with. "Last time…when you left…you said that you wanted to protect me, because I wasn't able to deal with the people that you fought against. You only let me rejoin you guys when I proved that I could stand up for myself. And, even then, you were hesitant about it. This time…I won't have any powers. I won't have the nanomachines. I'll have nothing. I will be just as weak and defenseless as a normal human being. When that happens…are you going to leave me?"

Sven didn't know what to say. It was true—if Eve went through with the transfusion, she would be left completely powerless and with no way of defending herself against the people that would, inevitably, come after Train. She would be in continual danger. However…he also knew that she wasn't one to give up so easily. She felt that she needed them, and she would do everything that she could to stay with them.

But, it wasn't just her who needed them. They needed her, too. At least…_he_ did. Losing Eve would be catastrophic, and he knew it. If he had been so attached to her when he had only known her for a couple of months, how much more attached was he after six years? They had been through so much together. He knew that he couldn't leave Eve, even if it was for the best.

Yes, he was selfish. But there were some things that he just couldn't deprive himself of.

When he had fallen silent, Eve's eyes had begun to fill up with tears. If he had nothing to say, it was probably because he wanted to leave her, and just didn't know how to tell her that. What good was a transfusion if she was just going to die, anyways? Sven leaving…would destroy her life as she knew it. She didn't think that she had the strength to rebuild it. The mere thought of such a situation left her nearly breathless. It was so devastating, she didn't even know how to deal with it.

Then, for the first time in years, Eve began to cry.

Sven's eyes widened as he saw the tears streaming down Eve's face. Most of the time, she was so mature and so much like an adult, it was hard to believe that she was eighteen years old. But, then, in that moment, he was taken back to when he had first met her. She had been twelve years old at the time. Their meeting had begun with her calling herself a demon, and had ended with her running him through with a large metal blade made of nanomachines. It was then that he had seen her cry and had realized that she was human, just like him. It was then that he had decided to save her.

As he watched the broken girl sob as she sat in a hospital bed, he had the exact same desire.

Reaching over, he wrapped his arms around her and pulled her into a tight, secure hug. Almost immediately, she stopped crying, mostly out of shock. In all the years that she had known Sven, she had never seen him give anyone physical comfort or show anyone physical affection. It just…wasn't Sven.

And, coincidentally, it was one of the very few things that she hated about him.

Letting out one more sob, she wrapped her arms around his waist and buried her head in his shirt. He was…warm…comforting…a welcome change after sitting alone in a stark, cold hospital room for hours on end. She had gotten so lonely, and she wasn't used to being alone. If all else failed, at least Train had always been good for a laugh. With Sven there, however…she forgot all of her fear of being alone. She _wasn't_ alone, and she knew that he wouldn't let her be.

Blowing out a deep breath, Sven rested his head against her hair—his hand rubbing up and down her back in a soothing motion. "I'm not going to leave you, Eve—not now, not ever. I promise you that."

A small smile came to rest on Eve's lips, and she let her eyes flutter shut. "I know, Sven…I know…"

She would go through with Tearju's operation. She figured that a dangerous chance at life was better than a one-way ticket to the underworld. It wasn't time for her to die. She still had so much to accomplish in her life. Even without the nanomachines…she could learn to live. It would be like learning to walk all over again, but…this time…Sven would be with her as she took he first steps. He would be there to guide her along.

She had nothing to fear. Sven never broke his promises.

—

**Author's Note**: Whoo-hoo. So, there it is, peoples. If you have any constructive criticism, please leave it for me—don't feel shy! I wrote this, literally, in the middle of the night. I probably need to fix it up in a few places. -sweatdrop-

'Til next time (if there is a next time)!


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